First stage turbine nozzle with erosion coating surface finish

ABSTRACT

A first stage turbine nozzle includes a first stage hub portion extending axially along a central axis, a first stage disk portion attached to the first stage hub portion and centered on the central axis, and a plurality of first stage vanes positioned radially around and attached to the first stage disk portion. Each vane extends a vane height H away from the first stage disk portion and each vane has a first end positioned at a diameter D away from the central axis. The first stage turbine nozzle also includes a plurality of first stage throats defined between radially adjacent first stage vanes. Each first stage throat has a throat width W between radially adjacent first stage vanes. The first stage turbine nozzle also includes a coating on a sidewall of each first stage vane, wherein a surface roughness of the sidewall is between 125 and 200 microinches Ra.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/584,499 filed Dec. 29, 2014 for “FIRST STAGE TURBINE NOZZLE WITHEROSION COATING SURFACE FINISH” by C. M. Beers and K. M. Rankin.

BACKGROUND

The present disclosure relates to aircraft environmental controlsystems. More specifically, the present disclosure relates to a firststage turbine nozzle for an air cycle machine.

Air cycle machines are used in environmental control systems in aircraftto condition air for delivery to an aircraft cabin. Conditioned air isair at a temperature, pressure, and humidity desirable for aircraftpassenger comfort and safety. At or near ground level, the ambient airtemperature and/or humidity is often sufficiently high that the air mustbe cooled as part of the conditioning process before being delivered tothe aircraft cabin. At flight altitude, ambient air is often far coolerthan desired, but at such a low pressure that it must be compressed toan acceptable pressure as part of the conditioning process. Compressingambient air at flight altitude heats the resulting pressured airsufficiently that it must be cooled, even if the ambient air temperatureis very low. Thus, under most conditions, heat must be removed from airby the air cycle machine before the air is delivered to the aircraftcabin.

Air cycle machines typically utilize turbine nozzles that can rotate todirect air in a radial direction with respect to a main axis of the aircycle machine. Turbine nozzles are typically coated with an erosioncoating to protect the turbine nozzles from damage. Erosion can becaused by particles in the air flowing through the air cycle machine.Applying a coating to the turbine nozzle will cause the coating to erodebut will protect the turbine nozzle from erosion. The coating can bereapplied as needed to fill areas that have eroded to extend the life ofthe turbine nozzle in the air cycle machine.

Turbine nozzles are typically cast, so prior to applying a coating,turbine nozzles have to be post-processed to smooth the turbine nozzle.Post-processing can include machining or sand blasting. The coating canbe applied using a number of different thermal spraying techniques,including detonation gun spraying and high velocity oxygen fuel (HVOF)spraying. Detonation gun spraying applies a coating using a detonationgun with a long water-cooled barrel. Oxygen, fuel, and powder are fedinto the barrel of the detonation gun and a spark is used to ignite theoxygen and fuel mixture. This will heat the powder and accelerate thepowder through and out of the barrel to be applied to a substrate. HVOFspraying applies a coating using a combustion chamber. A mixture of fueland oxygen is fed into the combustion chamber where it is ignited andcombusted continuously. The hot gas from the combustion will travelthrough a nozzle and a powder feed stock is fed into the gas stream inthe nozzle. The powder feed stock will partially melt and will flow outof the nozzle to be deposited on a substrate.

SUMMARY

A first stage turbine nozzle includes a first stage hub portionextending axially along a central axis, a first stage disk portionattached to the first stage hub portion and centered on the centralaxis, and a plurality of first stage vanes positioned radially aroundand attached to the first stage disk portion. Each first stage vaneextends a vane height H away from the first stage disk portion and eachfirst stage vane has a first end positioned at a diameter D away fromthe central axis. The first stage turbine nozzle also includes aplurality of first stage throats defined between radially adjacent firststage vanes. Each first stage throat has a throat width W betweenradially adjacent first stage vanes. The first stage turbine nozzle alsoincludes a coating on a sidewall of each first stage vane, wherein asurface roughness of the sidewall is between 125 and 200 microinches Ra.

A method of coating a first stage turbine nozzle includes casting afirst stage turbine nozzle with a first stage hub portion, a first stagedisk portion, and a plurality of first stage vanes, and applying anerosion coating to a cast sidewall of each of the plurality of firststage vanes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an air cycle machine.

FIG. 2 is a front plan view of a first stage turbine nozzle.

FIG. 3 is a side elevation view of the first stage turbine nozzle.

FIG. 4 is a break-away front plan view of the first stage turbinenozzle.

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of air cycle machine 10, which includesfan section 12, compressor section 14, first stage turbine section 16,second stage turbine section 18, tie rod 20, fan and compressor housing22, seal plate 24, first stage turbine housing 26, and second stageturbine housing 28. Also shown in FIG. 1 is axis Z.

Fan section 12, compressor section 14, first stage turbine section 16,and second stage turbine section 18 are all mounted on tie rod 20. Tierod 20 rotates about axis Z. Fan and compressor housing 22 is connectedto seal plate 24 and first stage turbine housing 26 with fasteners. Sealplate 24 separates flow paths in fan and compressor housing 22 from flowpaths in first stage turbine housing 26. First stage turbine housing 26is connected to second stage turbine housing 28 with fasteners. Fan andcompressor housing 22, first stage turbine housing 26, and second stageturbine housing 28 together form an overall housing for air cyclemachine 10. Fan and compressor housing 22 houses fan section 12 andcompressor section 14, first stage turbine housing 26 housing firststage turbine section 16, and second stage turbine housing 28 housessecond stage turbine section 18.

Fan section 12 includes fan inlet 30, fan duct 32, fan outlet 34, andfan rotor 36. Fan section 12 typically draws in ram air from a ram airscoop or alternatively from an associated gas turbine or other aircraftcomponent. Air is drawn into fan inlet 30 and is ducted through fan duct32 to fan outlet 34. Fan rotor 36 is positioned in fan duct 32 adjacentto fan inlet 30 and is mounted to and rotates with tie rod 20. Fan rotor36 draws air into fan section 12 to be routed through air cycle machine10.

Compressor section 14 includes compressor inlet 40, compressor duct 42,compressor outlet 44, compressor nozzle 46, and diffuser 48. Air isrouted into compressor inlet 40 and is ducted through compressor duct 42to compressor outlet 44. Compressor nozzle 46 and diffuser 48 arepositioned in compressor duct 42. Compressor nozzle 46 is mounted to androtates with tie rod 20 to compress the air flowing through compressorduct 42. Diffuser 48 is a static structure through which the compressorair can flow after it has been compressed with compressor nozzle 46. Airexiting diffuser 48 can then exit compressor duct 42 through compressoroutlet 44.

First stage turbine section 16 includes first stage turbine inlet 50,first stage turbine duct 52, first stage turbine outlet 54, and firststage turbine nozzle 56. Air is routed into first stage turbine inlet 50and is ducted through first stage turbine duct 52 to first stage turbineoutlet 54. First stage turbine nozzle 56 is positioned in first stageturbine duct 52 and is mounted to and rotates with tie rod 20. Firststage turbine nozzle 56 will extract energy from the air passing throughfirst stage turbine section 16 to drive rotation of tie rod 20.

Second stage turbine section 18 includes second stage turbine inlet 60,second stage turbine duct 62, second stage turbine outlet 64, and secondstage turbine nozzle 66. Air is routed into second stage turbine inlet60 and is ducted through second stage turbine duct 62 to second stageturbine outlet 64. Second stage turbine nozzle 66 is positioned insecond stage turbine duct 62 and is mounted to and rotates with tie rod20. Second stage turbine nozzle 66 will extract energy from the airpassing through second stage turbine section 18 to drive rotation of tierod 20.

Air is pulled into air cycle machine 10 with fan section 12. The airthat is pulled into air cycle machine 10 can be ambient air, air from aRAM air source, or bleed air from a gas turbine engine. This air cancontain particulate matter, such as water droplets, dust, or other fineparticles. The air is compressed in compressor section 14 by flowingthrough compressor nozzle 46. The air then expands as it flows throughfirst stage turbine nozzle 56 in first stage turbine section 16 andsecond stage turbine nozzle 66 in second stage turbine section 18. Todrive the air, compressor nozzle 46, first stage turbine nozzle 56, andsecond stage turbine nozzle 66 rotate with tie rod 20. As compressornozzle 46, first stage turbine nozzle 56, and second stage turbinenozzle 66 rotate, particulate matter in the air in air cycle machine 10can cause erosion of compressor nozzle 46, first stage turbine nozzle56, and second stage turbine nozzle 66. A coating is thus applied tocompressor nozzle 46, first stage turbine nozzle 56, and second stageturbine nozzle 66 to prevent erosion.

FIG. 2 is a front plan view of first stage turbine nozzle 56. FIG. 3 isa side elevation view of first stage turbine nozzle 56. FIG. 4 is abreak-away front plan view of first stage turbine nozzle 56. First stageturbine nozzle 56 includes first stage hub portion 70, first stage diskportion 72, plurality of first stage vanes 74, and plurality of firststage throats 76. Each first stage vane 74 includes first end 80, secondend 82, first face 84, second face 86, first sidewall 88, and secondsidewall 90. First stage turbine nozzle 56 also includes central axis Z.

First stage turbine nozzle 56 is made out of a durable material, such assteel, aluminum, or titanium. A coating, such as tungsten carbide, isalso applied to first stage turbine nozzle 56 to protect first stageturbine nozzle 56 from erosion. First stage turbine nozzle 56 includeshub portion 70, disk portion 72, plurality of vanes 74, and plurality ofthroats 76. Plurality of vanes 74 includes nineteen vanes.

Hub portion 70 forms a body portion of first stage turbine nozzle 56 andextends axially along central axis Z. Disk portion 72 is a disk shapedpart of first stage turbine nozzle 56 that extends radially outward fromcentral axis Z. Disk portion 72 includes a first face and a second face.The second face of disk portion 72 is connected to a first end of hubportion 70. Plurality of vanes 74 are positioned on the first face ofdisk portion 72 and are positioned radially around central axis Z offirst stage turbine nozzle 56. Each vane 74 extends a vane height H awayfrom the first face of disk portion 72. Vane height H is between 0.5300inches (1.3462 centimeters) and 0.5900 inches (1.4986 centimeters).Plurality of throats 76 are defined between radially adjacent vanes 74.Each throat has a throat width W between radially adjacent vanes 74.Throat width W is between 0.2730 inches (0.6934 centimeters) and 0.3050inches (0.7747 centimeters). First stage turbine nozzle 56 also includesa flow area A, which is the region through which the working fluid canflow. Flow area A is defined as the sum of flow areas Ai in each throat76 (flow area Ai as shown in FIG. 4). Flow area Ai is defined by vaneheight H and throat width W. Flow area A is between 2.7491 inchessquared (17.7362 centimeters squared) and 3.4191 inches squared (22.0583centimeters squared).

Each vane 74 includes first end 80 and second end 82. First end 80 ispositioned radially inward and second end 82 is positioned radiallyoutward. First ends 80 of plurality of vanes 74 are positioned diameterD away from center axis Z of first stage turbine nozzle 56. Diameter Dis between 7.5980 inches (19.2989 centimeters) and 7.6780 inches(19.5021 centimeters). Each vane 74 also includes first face 84 andsecond face 86. First face 84 is adjacent to disk portion 72 and secondface 86 is axially away from disk portion 72. Each vane 74 furtherincludes first sidewall 88 and second sidewall 90. Both first sidewall88 and second sidewall 90 extend from first end 80 to second end 82 ofeach vane 74. First sidewall 88 on one vane 74 faces second sidewall 90on an adjacent vane 74.

Table 1 below is a list of different ratios of dimensions, includingvane height H, throat width W, and diameter D.

TABLE 1 Ratios of dimensions Dimensions Minimum Ratio Maximum Ratio Vaneheight H to throat width W 1.7377 2.1612 Throat width W to diameter D0.0356 0.0401 Vane height H to diameter D 0.0690 0.0777

First stage turbine nozzle 56 is manufactured using a casting process.After the casting process, first stage turbine nozzle 56 can have asurface roughness up to 200 microinches Ra. In prior art processes, allsurfaces of first stage turbine nozzle 56 had to undergopost-processing, such as machining or sand blasting, prior to applying acoating to first stage turbine nozzle 56 so that the surface roughnessof first stage turbine nozzle 56 was less than 125 microinches Ra.

Using a HVOF spraying technique to apply the coating to first stageturbine nozzle 56 allows the coating to be applied directly to parts ofthe cast first stage turbine nozzle 56 without post-processing.Specifically, none of first sidewalls 88 of plurality of vanes 74 needto be post-processed when a HVOF spraying process is used to apply thecoating to first sidewalls 88 of plurality of vanes 74. This allows thecoating to be applied when the surface roughness of first sidewalls 88of plurality of vanes 74 is between 125 and 200. Using a HVOF sprayingprocess allows for increased hardness in the coating and it allows for ahigher percentage of tungsten carbide in the coating as opposed to othermaterials, such as cobalt. A HVOF spraying process also allows forgreater consistency in thickness of the coating as compared to otherthermal spraying techniques.

First stage turbine nozzle 56 is a high value component that isfrequently replaced due to damage of first stage turbine nozzle 56. Withprior manufacturing processes, every surface of first stage turbinenozzle 56 that was to be coated had to be post-processed prior to thecoating being applied. Post-processing every surface of first stageturbine nozzle 56 that is to be coated is a costly and time consumingprocess. Specifically, plurality of throats 76 are small spaces thatmakes it difficult to access first sidewalls 88 of plurality of vanes 74to machine or sand blast these surfaces. Using a HVOF spraying processto apply the coating eliminates this costly and time consuming process,as first sidewalls 88 of plurality of vanes 74 of first stage turbinenozzle 56 do not have to be post-processed prior to applying thecoating. This simplifies the manufacturing process and makes first stageturbine nozzle 56 more producible and less costly and time consuming tomanufacture.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments ofthe present invention.

A first stage turbine nozzle includes a first stage hub portionextending axially along a central axis, a first stage disk portionattached to the first stage hub portion and centered on the centralaxis, and a plurality of first stage vanes positioned radially aroundand attached to the first stage disk portion. Each first stage vaneextends a vane height H away from the first stage disk portion and eachfirst stage vane has a first end positioned at a diameter D away fromthe central axis. The first stage turbine nozzle also includes aplurality of first stage throats defined between radially adjacent firststage vanes. Each first stage throat has a throat width W betweenradially adjacent first stage vanes. The first stage turbine nozzle alsoincludes a coating on a sidewall of each first stage vane, wherein asurface roughness of the sidewall is between 125 and 200 microinches Ra.

The first stage turbine nozzle of the preceding paragraph can optionallyinclude, additionally and/or alternatively, any one or more of thefollowing features, configurations and/or additional components:

A further embodiment of the first stage turbine nozzle, wherein thecoating is a tungsten carbide coating.

A further embodiment of any of the foregoing first stage turbinenozzles, wherein the plurality of first stage vanes includes 19 vanes.

A further embodiment of any of the foregoing first stage turbinenozzles, wherein a ratio of the vane height H to the throat width W isbetween 1.7377 and 2.1612.

A further embodiment of any of the foregoing first stage turbinenozzles, wherein a ratio of the throat width W to the diameter D isbetween 0.0356 and 0.0401.

A further embodiment of any of the foregoing first stage turbinenozzles, wherein a ratio of the vane height H to the diameter D isbetween 0.0690 and 0.0777.

A further embodiment of any of the foregoing first stage turbinenozzles, wherein the diameter D is between 7.5980 inches (19.2989centimeters) and 7.6780 inches (19.5021 centimeters); the vane height His between 0.5300 inches (1.3462 centimeters) and 0.5900 inches (1.4986centimeters); and the throat width W is between 0.2730 inches (0.6934centimeters) and 0.3050 inches (0.7747 centimeters).

A further embodiment of any of the foregoing first stage turbinenozzles, wherein a flow area A is defined by a sum of the flow area ineach first stage throat in the first stage turbine nozzle.

A further embodiment of any of the foregoing first stage turbinenozzles, wherein the flow area A is between 2.7491 inches squared(17.7362 centimeters squared) and 3.4191 inches squared (22.0583centimeters squared).

An air cycle machine comprising a fan section with a fan rotor; acompressor section with a compressor nozzle; a first stage turbinesection with any of the foregoing first stage turbine nozzles; and asecond stage turbine section with a second stage turbine nozzle.

A method of coating a first stage turbine nozzle includes casting afirst stage turbine nozzle with a first stage hub portion, a first stagedisk portion, and a plurality of first stage vanes, and applying anerosion coating to a cast sidewall of each of the plurality of firststage vanes.

The method of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

A further embodiment of the method, wherein the plurality of first stagevanes includes 19 vanes.

A further embodiment of any of the foregoing methods, wherein the castsidewall of each of the plurality of first stage vanes has a surfaceroughness between 125 and 200 microinches Ra.

A further embodiment of any of the foregoing methods, wherein applyingan erosion coating to the cast sidewall is done using a high velocityoxygen fuel spraying process.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A first stage turbine nozzle comprising: a first stage hub portionextending axially along a central axis; a first stage disk portionattached to the first stage hub portion and centered on the centralaxis, wherein the first stage hub portion extends from a radially innerdiameter of the first stage disk portion and axially away from the firststage disk portion in a first direction; a plurality of first stagevanes positioned radially around and attached to the first stage diskportion, wherein each first stage vane extends a vane height H axiallyaway from the first stage disk portion in a second direction oppositethe first direction, and wherein each first stage vane has a first endpositioned at a diameter D away from the central axis and a sidewall ofeach first stage vane has a surface roughness between 125 and 200microinches Ra; a plurality of first stage throats defined betweenradially adjacent first stage vanes, wherein each first stage throat hasa throat width W between radially adjacent first stage vanes; and acoating applied directly on a cast surface of the sidewall of each firststage vane, wherein the coating is a high velocity oxygen fuelspray-deposited tungsten carbide coating, and wherein the cast surfacehas not undergone post-processing to reduce the surface roughness of thesidewall prior to the application of the coating.
 2. The first stageturbine nozzle of claim 1, wherein the plurality of first stage vanesincludes 19 vanes.
 3. The first stage turbine nozzle of claim 1, whereina ratio of the vane height H to the throat width W is between 1.7377 and2.1612.
 4. The first stage turbine nozzle of claim 1, wherein a ratio ofthe throat width W to the diameter D is between 0.0356 and 0.0401. 5.The first stage turbine nozzle of claim 1, wherein a ratio of the vaneheight H to the diameter D is between 0.0690 and 0.0777.
 6. The firststage turbine nozzle of claim 1, wherein: the diameter D is between7.5980 inches (19.2989 centimeters) and 7.6780 inches (19.5021centimeters); the vane height H is between 0.5300 inches (1.3462centimeters) and 0.5900 inches (1.4986 centimeters); and the throatwidth W is between 0.2730 inches (0.6934 centimeters) and 0.3050 inches(0.7747 centimeters).
 7. The first stage turbine nozzle of claim 1,wherein a flow area A is defined by a sum of the flow area in each firststage throat in the first stage turbine nozzle.
 8. The first stageturbine nozzle of claim 7, wherein the flow area A is between 2.7491inches squared (17.7362 centimeters squared) and 3.4191 inches squared(22.0583 centimeters squared).
 9. An air cycle machine comprising: a fansection with a fan rotor; a compressor section with a compressor nozzle;a first stage turbine section with the first stage turbine nozzle ofclaim 1; and a second stage turbine section with a second stage turbinenozzle.